Specifying a DVDRecorder

I am working on the specification of a DVDRecorder I am confusing with the a lot of system issues, especially the Audio Performance. Can anybody explain to me the difference between unweighted S/N and weighted S/R, channel separation as well as audio systems:- I read a lot in wikipedia, I found many resources but I lost my way and need a good guidence for initiatives! Can anybody tell me what are the important parameters in specifying RF, Audio and Video performance of a recorder and how to measure them??? Or just give me some straight forward links like wikipedia for beginners like me. Regards